最大子序列求和，二分法，欧几里得求余算法

/*standard binary search*/

template <typename T>

int binarySearch(const vector<T> & a,const T &x){

           int low = 0 , high = a.size()-1;

           while(low<=high){

                     int mid = (low+hign)/2;

                     if(a[mid]<x){

                                  low  = mid+1;

                     }

                     else if(a[mid]>x){

                                 high = mid -1 ;

                      }

                      else{

                                   return mid;

                       }

           }

           return  -1;

}

 

 

/*gcd   最大公约数*/

long gcd(ong m,long n){

           while(n!=0){

                    long rem = m%n;

                    m = n;

                    n =rem;

           }

           return m;

}